Co-ordination of recombination and allelic exclusion at IgH and Igk loci

描述（由申请人提供）：如何在发育中的B淋巴细胞的复杂染色质环境中保持忠实的DNA重排的分子细节是我实验室正在进行的研究的重点。我们有新的数据表明IgH基因座是由IG？基因座，并已确定参与两个IG？？调节元件，3'E？？增强子和Sis（间插序列中的沉默子。调节是通过短暂的协会的两个位点在亲前B细胞的过渡时，重组酶的目标是远离IgH位点的IG？基因座我们的目标是阐明这两个位点之间的关联的功能意义，并了解在分子上的细节如何实现协会。我们的假设是IgH和IG？基因座在实施IgH基因座的等位基因排除中起着核心作用，这对于维持重组过程的完整性和确保基因组稳定性至关重要。由于重组失调和等位基因排斥可导致免疫缺陷、自身免疫和涉及IG位点的易位，因此了解其潜在机制至关重要。此外，这些研究对整个基因调控具有重要影响。公共卫生相关性声明：免疫球蛋白（IG）基因的有序重排是获得性免疫所必需的高度调节的过程，通过等位基因排除来协调B和T淋巴细胞受体的表达，确保克隆性，同时保护基因组免受这些固有不稳定的重组事件的影响。如何在发育中的B淋巴细胞复杂的染色质环境中维持忠实的DNA重排的分子细节是我实验室正在进行的研究的重点。我们最近的研究表明，臂间IG？等位基因指导未重排的IgH等位基因朝向共享的着丝粒周围簇。协会的两个位点在这种压抑性的环境中随后诱导IgH基因座上的非功能性等位基因的decontraction。这确定了一个新的机制，协调可访问性和表达的变化。待检验的假设是，协会的IgH和IG？基因座在实施IgH基因座的等位基因排除中起着核心作用，这对于维持重组过程的完整性和确保基因组稳定性至关重要。本研究旨在从分子水平上详细了解IG基因座的关联对等位基因排斥和基因组稳定性的作用机制。了解两个基因座的变化是如何协调的，并确定所涉及的途径在该领域是至关重要的，因为重组和等位基因排斥的失调可导致免疫缺陷，自身免疫和涉及IG基因座的易位。这些研究为免疫球蛋白基因转录和重排的基本机制提供了新的细节，并描绘了一幅高度动态和有序的核结构图，这将对基因调控产生重要影响。

DESCRIPTION (provided by applicant): The molecular details of how faithful DNA rearrangements are maintained in the context of the complex chromatin environment of the developing B lymphocyte is the focus of ongoing research in my lab. We have new data indicating that the IgH locus is regulated by the Ig??locus and have identified the involvement of two Ig??regulatory elements, the 3'E??enhancer and Sis (silencer in the intervening sequence. Regulation is achieved through transient association of the two loci at the pro- to pre-B cell transition when the recombinase enzymes are targeted away from the IgH locus to the Ig? locus. We aim to elucidate the functional significance of association between the two loci and to understand in molecular detail how association is achieved. It is our hypothesis that association of the IgH and Ig??loci plays a central role in enforcing allelic exclusion of the IgH locus, which is critical for maintaining the integrity of the recombination process and ensuring genome stability. Because de-regulation of recombination and allelic exclusion can result in immune deficiency, autoimmunity and translocations involving Ig loci, it is essential to understand the underlying mechanisms. In addition these studies have important implications for gene regulation as a whole. Public Health Relevance Statement: The ordered rearrangement of immunoglobulin (Ig) genes is a highly regulated process essential for adaptive immunity, orchestrating the expression of B and T lymphocyte receptors through allelic exclusion that ensures clonality, all the while protecting the genome from these inherently unstable recombination events. The molecular details of how faithful DNA rearrangements are maintained in the context of the complex chromatin environment of the developing B lymphocyte is the focus of ongoing research in my lab. Our recent studies indicate that the pericentric Ig? allele directs the unrearranged IgH allele towards a shared pericentromeric cluster. Association of the two loci in this repressive environment subsequently induces IgH locus decontraction on the non-functional allele. This identifies a novel mechanism for co-ordinating changes in accessibility and expression. The hypothesis to be tested is that association of IgH and Ig? loci plays a central role in enforcing allelic exclusion of the IgH locus, which is critical for maintaining the integrity of the recombination process and ensuring genome stability. The aims in this grant are designed to understand in molecular detail the mechanisms by which association of Ig loci contributes to allelic exclusion and genome stability. Understanding how changes at the two loci are co-ordinated and identifying the pathways involved is of fundamental importance in the field because de-regulation of recombination and allelic exclusion can result in immune deficiency, autoimmunity and translocations that involve Ig loci. These studies provide new detail to the basic mechanisms linking immunoglobulin gene transcription and rearrangement and paint a picture of a highly dynamic and ordered nuclear architecture that will have important implications for gene regulation in general.